This invention relates to an external housing for an exhaust muffler for internal combustion engines, comprising at least one pipe section which has at one end a seamlessly merging bottom and at least one connecting piece likewise seamlessly therefrom.
The exhaust muffler according to the invention is to be used preferentially on motor vehicles.
In a known external housing of the assumed kind (described in German [Fed. Rep.] Offenlegungsschrift No. 25 20 301), the bottom and the connecting piece starting therefrom are formed in one piece on the pipe section in question by tapering the respective end of the pipe section by swaging. The swaging can be done over a mandrel or also without a mandrel in a cold shaping or hot shaping operation. This known external housing has several disadvantages. Not only does the shaping of the pipe socket by swaging require expensive tools for exact production; it is also labor-intensive and complicated. The bottom can extend conically outward only to an angle of about 45.degree., so that the production of other forms for the bottom, e.g. a bottom extending substantially perpendicular to the pipe axis, is not possible with the known manufacturing methods.
An exhaust muffler for internal combustion engines has become known (described in German [Fed. Rep.] Offenlegungsschrift No. 26 53 732) wherein the tubular housing consists of an aluminum hollow section made by extrusion. However, in this known exhaust muffler the two end-face housing covers are formed as separate parts, which must be screwed to the tubular base housing. The external housing of the known exhaust muffler thus consists of several differently formed parts which must be assembled. This makes the known design more expensive.